This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To use PET to assess the effects of sleep deprivation in brain dopaminergic function and to relate this to its cognitive and behavioral effects. We hypothesize that sleep deprivation will upregulate the dopamine transporter (DAT). To use fMRI to investigate the blood oxygenation level dependent (BOLD) response during verbal working memory and visuospatial attention in sleep deprived subjects. We hypothesize that during sleep deprivation, the activations in the prefrontal and parietal cortices will be significantly decreased and these abnormalities would correlate impaired task performance.